The overall aim of the project is to examine the clinical and cost-effectiveness of utilizing booster sessions(periodic face-to-face follow-up appointments that take place several weeks or months following discharge from the supervised therapy program designed to review the patient's current rehabilitation program, troubleshoot any problems with the program, and make recommendations for program progression or modification) in the delivery of exercise therapy, and supplementing exercise therapy with manual therapy techniques(manually applied treatment techniques such as joint mobilization/manipulation, manual traction, soft tissue manipulations, passive stretching and range of motion). The investigators will do this in a randomized, multi-center, clinical trial. The investigators hypothesize that adding manual therapy techniques will be more clinically effective than exercise alone and that using booster sessions will maintain longer term clinical effects and be more cost-effective than not using booster sessions.